AGK Electrics Flashcards by Oliver Cox

How is electric produced onboard and how much do they produce?

Generator (x2) - 90KvA each

External Power - unlimited

APU - 90KvA

Ram Air Turbine (RAT) (Emergency Gen) - 5KvA

Batteries - 1KvA (C Rated)

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What is the hierarchy of power?

If one system shuts down, it will go to the next power source

In a downward movement

Gen
Ext
APU
RAM
Batteries

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Draw the A320 Schematic

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What does TRU stand for ?

Transformer Rectifier Unit (TRU)

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What happens if AC1 fails?

AC2 then provides power to the A CESS bus

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What is electricity?

Flow of electrons through a conductive material

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Atomic Structure

+ Proton
N Neutron
- Electron

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What is a chain reaction?

As one electron moves, the one behind it goes into its place, domino effect (think of class mates moving one seat to the right)

The flowing of electrons creates electricity

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What causes chain reactions and which provide sufficient power?

Heat - thermocouple
Magnetic Field (moving) - Generator
Chemical Reaction - Battery
Pressure - piezo electric crystals - vibration sensors
Light - solar
Friction - Static electricity

Magnetic field (moving) and chemical reactions provide sufficient power

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Direct Current

Electrons flow in a single direction

Good at low range
Low voltage

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DC graph

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AC graph

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Alternating Current

Electrons flow in both directions around the circuit

Travels further as it ignores resistance

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What is Voltage and what can it also be called?

Electrical pressure

Potential Difference (P.D.)
Electro-motive Force (EMF)

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DC systems

Computers
Screens
Radios
Lights (Navigation)

Good at low range

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AC systems

Fuel pumps
Air conditioning packs
Wx Radar
Galleys
Windcreens
~115,000V, 43C = malleable (flex)
~On ground - Single phase
~In flight - Three phase

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What is current and how’s it measured?

Flow rate

Amperes (Amps)
I

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What is resistance?

Counteracts flow of current

Ohm
Ω
R

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Ohms Law equation triangle

V = Volts
I=Current
R= Resistance

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What is power and what are there equations?

Electrical work

P(Watts) = V x I

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SEP electrical system

12V DC electrical system

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MEP electrical system

24V DC electrical system
115v AC from inverter

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A320/B737 B757/B767 electrical system

115/200V 3 phase A at 400Hz
+
24V DC system

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What is load shredding?

Process of turning off loads you cannot power
~e.g galley

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What is frequency?

Rate of change Positive to negative cycle F = Hertz (Hz) 1Hz = 1 cycle/sec

What Is A320/B737 frequency and why?

Constant frequency at 400Hz Why? More stable power Smaller generator (can fit onto engine)

Intrinsic relationship between magnetism and electricity

A magnetic field can create electricity Electricity can create a magnetic field

What is inductance?

Generation of electricity using a magnetic field

What effects voltage?

Speed of movement Angle at which the conductor cuts the field Diameter of the conductor Strength of the field

What is Lorentz Law?

F = B L I F = Force B = Field Strength L = Length of the conductor I = Resultant Current

What is Capacitance?

The ability of a circuit or component to hold a charge

What is a capacitor also know as and what does it do?

Condenser Holds charge for a short amount of time

What does a Capacitor measure in?

Farads (F)

What determines capacity (Capacitor)

Distance between plates Dielectric constant Surface area of the plates

Capacitor Circuit

Top half = stage 1 Bottom half stage 2 Once capacitor is charged from battery, the switches open and the electricity travels through the bottom half to light the bulb Then the circuit closes and top half circuit is in used until the capacitor is charged again

To charge the capacitor, you must

Increase frequency

What is a Resistor?

A component designed to provide a predictable resistance Can be used to control voltage and/or current

Series circuit

Rt = R1 + R2 + R3 If R1 fails then they all fail > not used often in aviation

Parallel Circuit

1 /Rt = 1/R1 + 1/R2 = 1/R3 Answer as a fraction unless specified

What are the three circuit states?

Closed Open Short (failure)

Which way is the electron flow in a conventional/non conventional circuit?

Con - +ve to -ve Non Con - -ve to +ve

What happens in a short circuit?

Resistance decreases but current increases

What does a circuit breaker do?

Protects against over current

Characteristics and materials of conductors

Copper Gold Aluminium Low resistance Abundance of free electrons (weak bond between electron and nuclei, easy to move)

Characteristic and materials of an insulator (Dielectric)

Air Paper Rubber Glass Low or no free electrons

What is static electricity?

Air molecules, snow and ice rub against fuselage, depositing electrons

When is static electricity most likely to occur?

Dry conditions with low humidity

What happens if static builds up and how do we prevent this?

Creates a rapid violent discharge back to atmosphere Prevent by installing STATIC WICKS

What is a static wick?

Constructed of wire or carbon BOLTED TO FRAME Wicks deposit the static electricity into the clouds on decent If a/c experiences a large discharge, some may fall off A/c deemed grounded if 3 or more are missing

What is a bonding cable?

Joins all parts if the airframe together Ensures low resistance path to static wicks Allows a/c to be at the same voltage as static builds up Prevents radio interference